But did you know: Public radio is at a crucial intersection, Ellen Gamerman writes: Both its hosts and audiences are aging, and its business model is getting more competition from smaller podcasting companies with aggressive advertising strategies. That’s leading to tension between those in public media who are “clinging” to traditional broadcast shows such as “Car Talk” or “A Prairie Home Companion” and those who believe in a podcasting-based future for NPR. VP of content and programming at Chicago’s WBEZ and former “This American Life” producer Ben Calhoun says: “It’s a moment of anxiety systemwide. … There’s a tendency for that dynamic to manifest as sort of protectionist and defensive.”